Mosquito Update - Chikungunya Virus

Mosquito activity will continue to rise as populations in rain-filled breeding sites mature and emerge as adults.  The recent media coverage about Chikungunya virus has sent many people into a frenzy buying all sorts of  traps or repellent devices for "controlling" mosquitoes.  There are a lot of products and homemade remedies being pushed as *the* fix to mosquito problems and so it's a good time to remind people of that well-worn adage about "If it sounds too good to be true.....".    For example, there is one product (that I won't mention in the interest of avoiding confrontation) whose website talks about its natural ingredient and how university-based research demonstrated that it repels mosquitoes.  The point to note is that they don't talk about their *product* being university-tested and proven to be effective. They leave it to the reader to assume that showing the chemical works means their product works similarly (which is not always the case).  So, people need to be smart consumers and read the website or product package (if they buy it locally) before they purchase one of these kinds of products.  We strongly recommend personal protection in the form of repellents, but we also recommend using a product with proven efficacy AND using it according to the product label.  We have a list of common products on our web page:http://insects.ncsu.edu/Urban/repellents.htm     

A little about repellents - they keep mosquitoes from biting you but they don't do anything to get rid of mosquitoes.  Think about mosquito repellents like a highway detour.  You exit the highway, grumble a lot about it in the process, but inevitably you get to your destination and you may have actually found some place to stop and eat during the detour.  So, while wearing a repellent keeps you from getting bitten, the mosquito will likely detour and feed on someone else (or some other animal such as a bird, squirrel, etc.) and then lay eggs in some source of standing water.   This brings us back to the same list of suggestions that we tell people every time we talk about mosquito *management*: 

- Get rid of standing water wherever possible

- Be careful when treating mosquito resting/landing sites on foliage, lawns, etc., particularly when plants are in bloom and bees are out there visiting flowers.

- When using outdoor area foggers, avoid chemical drift.  Remove (or at least cover)  food prep equipment such as grills, as well as children's toys (and the children) along with your pets and their food/water bowls. Do not allow chemical to drift onto other people's property.

Why is Chikungunya virus less of a threat at this time?  Some people assume that it's similar to Ebola virus which has garnered much attention because it is a highly contagious and usually lethal disease that is spread directly from person to person.  In contrast, Chikungunya virus has to be transmitted by a mosquito.  So, a mosquito has to bite an infected person  and acquire the virus (which doesn't necessarily happen), then lay eggs before it bites another person and transfer the virus to them.  So,currently (and fortunately) there is a limited supply of infected people in the US for the mosquitoes to bite and most of those people have sought medical treatment for the disease.  This disease cycle is also different from the more common mosquito-borne diseases such as West Nile Virus (WNV) because WNV usually resides in a ready supply of "reservoir hosts" - birds, which keep the virus present in areas of the country.  So, when a mosquitoes bite infected birds and subsequently bite people (and not all mosquito species feed on both birds and people), we see infection rates climb.

The bottom line is that Chikungunya virus is not a major threat in North Carolina but that does not mean people should neglect protecting themselves from mosquito bites because we have other diseases present and I expect that we'll hear of a few cases of LaCrosse Encephalitis (likely in western NC) or EEE showing up in horses within the next 2-3 weeks and likely in southeastern NC (but hopefully my prediction will be wrong).

Michael Waldvogel, PhD
Extension Assoc. Professor & Specialist, Structural & Industrial Pests
North Carolina State University
Dept. of Entomology, Box 7613, 100 Derieux Place
Raleigh, NC USA 27695-7613